WASHINGTON (AFP) - The United States reaffirmed Wednesday a weekend deadline for Iran to give a final answer to world powers seeking a breakthrough in the nuclear crisis, warning of consequences on any defiance by the Islamic republic. Iran was given a two-week deadline expiring Saturday to give a final answer to a package of incentives offered by the five permanent UN Security Council members plus Germany aimed at persuading it to freeze its sensitive nuclear activities. But Iran has rejected any deadline, saying it was only agreed that it would during a two-week period examine the proposal put forward by the international community. The US State Department said Wednesday that the Iranians were aware of and had acknowledged the Saturday deadline following talks in Geneva on July 19 with representatives of the six powers, including EU foreign policy chief Javier Solana. Asked about Tehran's insistence that it was not subject to any deadlines, contrary to expectations of the international community, State Department spokesman Sean McCormack said, "There are consequences diplomatically for defying the just demands of the Security Council. "It's clear. This is the other side of the two-track approach," he said referring to the longstanding carrot and stick approach pursued by world powers in dealing with Iran's refusal to end uranium enrichment, a process that could be used to develop a nuclear bomb. "Nobody is really desirous of going down that pathway. The P-5 plus one does not want it," McCormack said. But he warned, "This is serious stuff and we along with the P-5 plus one are absolutely prepared to go down that pathway should the Iranian regime take the world down that pathway." McCormack's spoke after Iran's supreme leader Ayatollah Ali Khamenei said on Wednesday that the country will not retreat in the face of demands by world powers for Tehran to halt enrichment activities. "Taking one step back against arrogant (powers) will lead to them to take one step forward," Khamenei was quoted as saying by state television in a sermon. "The idea that any retreat or backing down from righteous positions would change the policies of arrogant world powers is completely wrong and baseless," said Khamenei, who has the final say on all key policy issues in Iran. Meanwhile, White House hopeful Barack Obama has told fellow Democratic lawmakers that Israel will launch a military strike on Iran if nuclear sanctions fail, ABC News reported Wednesday. The comment was reportedly made in a meeting late Tuesday between Senator Obama and Democratic members of the House of Representatives, following the presidential contender's return from an overseas tour that included Israel. "Nobody said this to me directly but I get the feeling from my talks that if the sanctions don't work, Israel is going to strike Iran," an attendee at the meeting quoted Obama as saying, according to ABC. Neither the Obama campaign nor his Senate office had any immediate comment. Obama also told Tuesday's meeting that Arab states understood that a nuclear Iran would be a "game changer" for the entire region because of likely Israeli action, another attendee cited by ABC said. Visiting Paris as part of his foreign tour, which also took in Jordan, Obama said Friday that Iran should not wait for the next US president to be elected to resolve its nuclear dispute with the West. "Iran should accept the proposals that President (Nicolas) Sarkozy and the EU... are presenting now. Don't wait for the next president," he said at a joint press conference with Sarkozy.